Electrical cable



Jan. 12, 1932. A, JOHNSON 1,841,130

ELECTRICAL CABLE Filed Feb. 11, 1929 anvamtoz 4, M4%A-7*V.M7,

Patented Jan, 12, 1932 UNITED STATES PATENT OFFICE eus'rnvn A. aonnson, or mvine ron, naw amen Emcrmcn. cum

Application filed February 11, .1829. Serial No. 838,966.

cable which may be easily and economically manufactured, and one which is peculiarly adapted for convenient installment in a house or building.

It is a further object of the invention to provide a cable which will satisfy the specifications and requirements of the various associations of fire insurance underwriters which examine and pass on electrical equipment designed for use in building construction.

Other objects and advantages of the invention will appear hereinafter.

A preferred embodiment of the invention selected for purposes of illustration is shown in the accompanying drawings, in which,

Figure 71 is. a view of apiece of armored cable F Figure 2 is a similar view showing the armor removed from the end of the cable preparatory to attachment to an outlet box.

Figure 3 is a similar view showing the removal of the paper wrapping.

Figure 4 is a similar view showing the cable ready for attachment, and

Figure 5 is a plan view of the washer.

Referring to the drawings, the cable comprises, in the specific embodiment illustrated, a pair of conductors 1 and 2 of copper or other suitable conductive material, which said conductors are each surrounded with suitable insulating material such as therubber jackets 3 and the braided fabric jackets 4.

Preferably the insulated pair is twisted slightly and the twisted pair is wra ped and 4 bound relatively tightly together y means of a paper wrapping 5 which may be conveniently applied in the form of a spirally wound strip or tape. The paper of which said wraping is formed may be of any desired quality, at is preferabl a kraft stock which is creped so as to provi e a certain degree oi-stretch without rupture when the cable is bent at a sharp angle. Preferably the paper strip or tape is coated with adhesive on at least one face, so that preferably ap wrapping, w rch wrapping is preferably apo outlet box.

during the wrapping operation the overlapping edges may be caused to adhere one to another, thus forming in effect a closed paper tube surrounding and enclosing the insulated conductors. I a

If desired, the paper of which the wrapping is formed may also be coated or impregnated with suitable moisture and flame'proo ing materials, but these materials are well known in the art and form no present invention.

The metal armor 6 is applied to the cable directly over the paper wrapping 5, and is plied in the form of a spiral part of the o plied with suflicient tightness to hold the wrapped pair of conductors with some firmness, thus preventing slipping of the conductors within the metal casing.

In using cable of the armored type illus- 7o trated herein, it is customa in making connections to outlet boxes an the like to first cut away the armor atthe end of the cable, as illustrated in Figure 2, and then in the case of paper wrapped conductors, such as dis- (6 closed herein, to remove the paper wrapping from the exposed ends of the conductors, thus leaving the ends of the conductors free for connection to terminals, etc. within the It is common practice among electricians to use hack shaws to cut the metal armor and this results in most cases in leaving jagged metal edges which are apt to injure the insulation of the conductorsfi-lt has been found that a paper wrappin such as that disclosed herein provides excel ent protection against such injuries to the insulation if the user is careful to remove it only to a point near to, but not quite at, the severed metal edge, but it has sometimes been difiicult to prevent the paper from being pulled out from the space between the insulated conductors and the metal armor, thus leaving the conductors free to chafe against the jagged edges of the armor.

Accordingly, as a feature of the present invention, it is proposed to provide convenient -means to limit the removal of the paper wrapping to any desired extent. In the preioc Eerred embodiment illustrated the said limitmg means comprises a flat disk or washer 7 having an elongated aperture 8 formed therein so that the washer may be threaded over the wound ends of the conductors as illustrated in Figures 2, 3 and 4. In use, the washer may be moved along the conductors until it contacts with the severed ends of the metal armor. In order to remove the paper wrapping, the paper may then be slit near the ends of the conductors and by grasping the ends of the conductors and pulling them apart as illustrated in Figure 3, the paper may be quickly ripped, after which the paper fragments may be removed from the conductors. As will be observed, however, even though this'operation may be performed very very carelessly, the washer limits the tearing of the paper and prevents the removal of the paper beyond the point where the washer is located, unless with deliberate intent. Thus the paper jacket remains intact to a point beyond the edge of the armor and serves to protect the insulated conductors from the jagged edges thereof.

It will also be noted that during the rip ping operation, as illustrated in Figure 3, the washer serves to prevent the conductors from being bent over into contact with the uppermost edge or corner of the metal armor. The washers may be made of any suitable material, but art preferably made of some insulating material such as compressed fiber.

It will be understood that the invention may be variously modified and embodied within the scope of the subjoined claim.

I claim as my invention:

Electrical cable comprising, in combination, a pair of insulated electrical conductors, a paper wrapping surrounding said conductors and binding them together, a metal armor surrounding said wrapped conductors said paper wrapped conductors extending beyond the end of said armor, and a flat disk of insulating material having an aperture therein closely surroundin said wrapped conductors and positioned lntermediate the end of said armor and the ends of said paper wrapped conductors, whereby the removal of the paper wrapping therefrom is limited.

In testimony whereof, I have signed my name to this specification this 9th day of F ebruary, 1929.

GUSTAVE A. JOHNSON. 

